I use Aqueon Aquarium Plant Food, sometimes with Seachem Excel in the morning because it is a CO2 booster, no point putting it in at night. The plants are growing alright.

My boss let me try his Aqua Design Group's liquid Potassium and Green Brightly liquid fert. It's like my plants were growing on steroids in one day. But that stuff is expensive. He uses the ferts for the RCS 2.5g NPT in his office.

I stuck one of the sea chem root tabs next to a banana plant I have in the aquarium. The plant is now sprouting roots like crazy and it has leaves and "banana's" that are bigger and look nicer than when it was in the store... so the seachem tabs are good if you have inert substrate and no actual mineral medium in the tank or as an additive to an npt.